Anomalous Weather Conditions Research Articles

Strain variation and anomalous climate synergistically influence cholera pandemics.

Explanations for the genesis and propagation of cholera pandemics since 1817 have remained elusive. Evolutionary pathogen change is presumed to have been a dominant factor behind the 7th "El Tor" pandemic, but little is known to support this hypothesis for preceding pandemics. The role of anomalous climate in facilitating strain replacements has never been assessed. The question is of relevance to guide the understanding of infectious disease emergence today and in the context of climate change. We investigate the roles of climate and putative strain variation for the 6th cholera pandemic (1899-1923) using newly assembled historical records for climate variables and cholera deaths in provinces of former British India. We compare this historical pandemic with the 7th (El Tor) one and with the temporary emergence of the O139 strain in Bangladesh and globally. With statistical methods for nonlinear time series analysis, we examine the regional synchrony of outbreaks and associations of the disease with regional temperature and rainfall, and with the El Niño Southern Oscillation (ENSO). To establish future expectations and evaluate climate anomalies accompanying historical strain replacements, climate projections are generated with multi-model climate simulations for different 50-year periods. The 6th cholera pandemic featured the striking synchronisation of cholera outbreaks over Bengal during the El Niño event of 1904-07, following the invasion of the Bombay Presidency with a delay of a few years. Accompanying anomalous weather conditions are similar to those related to ENSO during strain replacements and pandemic expansions into Africa and South America in the late 20th century. Rainfall anomalies of 1904-05 at the beginning of the large cholera anomaly fall in the 99th percentile of simulated changes for the regional climate. Evolutionary pathogen change can act synergistically with climatic conditions in the emergence and propagation of cholera strains. Increased climate variability and extremes under global warming provide windows of opportunity for emerging pathogens.

Cryogenic cave minerals recorded the 1889 CE melt event in northeastern Greenland

Abstract. The investigation of cryogenic cave minerals (CCMs) has developed in recent decades to be a particularly valuable proxy for palaeo-permafrost reconstruction. Due to difficulties, however, in obtaining reliable chronologies with the so-called “fine” form of these minerals, such studies have thus far utilised the “coarse” form. In this study, we successfully investigate the northernmost-known deposit of fine-grained CCMs, which are situated in Cove Cave (Greenlandic translation: Eqik Qaarusussuaq), a low-elevation permafrost cave in northeastern Greenland (80∘ N). The Cove Cave CCMs display a complex mineralogy that consists of fine-grained cryogenic cave carbonates and sulfate minerals (gypsum, eugsterite, mirabilite, and löweite). Until now, previous attempts to date fine-grained CCMs have been unsuccessful; however, here we demonstrate that precise dating is possible with both isochron-based 230Th / U dating and 14C dating if the dead carbon fraction is reliably known. The dating result (65±17 a BP; 1885±17 CE) shows that the Cove Cave CCMs formed during the late Little Ice Age, a time interval characterised by cold temperatures and abundant permafrost in northeastern Greenland, making water infiltration into Cove Cave dependent on the water amount and latent heat. We relate the CCM formation to a combination of black carbon deposition and anomalously high temperatures, which led to widespread melting over large areas of the Greenland ice sheet in the course of a few days. We propose that the anomalous weather conditions of 1889 CE also affected northeastern Greenland, where the enhanced melting of a local ice cap resulted in water entering the cave and rapidly freezing. While calcite and gypsum likely precipitated concurrently with freezing, the origin of the other sulfate minerals might not be purely cryogenic but could be linked to the subsequent sublimation of this ice accumulation in a very dry cave environment.

Effects of Extreme Temperature and Precipitation Events on Daily CO2 Fluxes in the Tropics

The effects of anomalous weather conditions (such as extreme temperatures and precipitation) on CO2 flux variability in different tropical ecosystems were assessed using available reanalysis data, as well as information about daily net CO2 fluxes from the global FLUXNET database. A working hypothesis of the study suggests that the response of tropical vegetation can differ depending on local geographical conditions and intensity of temperature and precipitation anomalies. The results highlighted the large diversity of CO2 flux responses to the fluctuations of temperature and precipitation in tropical ecosystems that may differ significantly from some previously documented relationships (e.g., higher CO2 emission under the drier and hotter weather, higher CO2 uptake under colder and wetter weather conditions). They showed that heavy precipitation mainly leads to the strong intensification of mean daily CO2 release into the atmosphere at almost all stations and in all types of study biomes. For the majority of considered tropical ecosystems, the intensification of daily CO2 emission during cold and wet weather was found, whereas the ecosystems were predominantly served as CO2 sinks from the atmosphere under hot/dry conditions. Such disparate responses suggested that positive and negative temperature and precipitation anomalies influence Gross Primary Production (GPP) and Ecosystem Respiration (ER) rates differently that may result in various responses of Net Ecosystem Exchanges (NEE) of CO2 to external impacts. Their responses may also depend on various local biotic and abiotic factors, including plant canopy age and structure, plant biodiversity and plasticity, soil organic carbon and water availability, surface topography, solar radiation fluctuation, etc.

Evidence of sweet corn yield losses from rising temperatures

Crop production is sensitive to anomalous weather conditions, but vegetable crops can be highly sensitive to environmental changes. Using sweet corn data collected on 16,040 fields over a 27-year period, we: (a) estimate yield sensitivities to changes in growing season temperature and total precipitation, (b) estimate critical thresholds in non-linear temperature effects on sweet corn yield across diverse environments, and (c) quantify yield losses from surpassing the upper temperature threshold during anthesis in sweet corn. Our results show growing-season temperatures exceeding 30 ^circ{rm C} were detrimental to crop yield. Each additional degree day spent above 30 ^circ{rm C} during anthesis reduced crop yields by 0.5% and 2% in irrigated and rainfed fields, respectively. This study shows evidence for sweet corn yield losses across broad spatial domains in the wake of climate change and underscores the urgency to accelerate crop adaptation strategies to sustain production of this highly popular crop.

The impact of the large-scale circulation anomalies in the northern hemisphere on air quality in Wuhan of China during the Spring Festival in 2020

During the 2020 Chinese Spring Festival extended holidays and the COVID-19 period in Wuhan, the “quasi-zero emissions increase” occurred due to the human activities have a considerably lower impact on air quality. A new scientific question of concern: Why has high of O3 and PM2.5 still been observed? The comparative analysis of the influences of anomalous atmospheric circulation and weather conditions during this special period in 2019–2020 with those in the historical years can be useful. The results in the study were as follows:(1) Even during this “quasi-zero emissions increase” period, the concentrations of O3 and PM2.5 are higher than normal, with O3 being significantly higher in Wuhan. Which is associated with a anomaly large-scale humid/warm water vapor transport in the Northern Hemisphere which is significantly different from that of the same period with historical more-haze years. (2) In this scenario, the large-scale humid/warm water vapor transport brings sustained high-humidity water vapor lifting conditions to north China. The daily cycling change of the sun's zenith angle to support the high-humidity and high-condensation condition are conducive to the elevation of high condensation (fc) and degree of super-saturation (S) going up to the peak of S >10%. Under the condition driven by high fc, it causes the power exponent law to be followed converting NO2 to O3, thereby resulting in an increase in O3 concentration. This additional contribution to O3 concentration is as high as 37% than those from pure chemical process. (3) An objective quantitative reversal method for calculating the monthly threshold in fc is given based on the power exponential conversion law by the observed data. It can be prospectively applied to assess the feedback on the impact of pollution on urban climate.

Response of Spruce Forest Ecosystem CO2 Fluxes to Inter-Annual Climate Anomalies in the Southern Taiga

Climate extremes and anomalies modify the CO2 ecosystem–atmosphere exchange of the boreal forests and consequently alter the terrestrial carbon stocks and the atmospheric greenhouse gas concentrations. The effects of the anomalous weather conditions on the CO2 net ecosystem exchange (NEE), total ecosystem respiration (TER), and gross primary production (GPP) of the typical southern taiga nemorose spruce forest were analyzed using continuous eddy covariance flux measurements in the 2015–2020 period. The forest was found to be a source of atmospheric CO2 in 2016, 2017, 2019, and 2020 (the mean annual GPP/TER ratio was between 0.87 and 0.97). In 2018, the forest was found to act as a CO2 sink (GPP/TER = 1.47) when a positive temperature anomaly in the growing season was accompanied by a negative precipitation anomaly and increased global radiation. The early start of the CO2 uptake in the anomalously warm winter of 2019/2020 did not result in an increase in the annual GPP/TER ratio (0.90). The comparison of the flux data obtained from the nemorose spruce forest on the well-drained soils with the data obtained from paludified spruce forest in the same landscape showed that the mean annual GPP/TER ratio of the sites alternatively responded to the mentioned anomalies. This study suggests that a variety of soil moisture regimes across the southern taiga spruce forests provide a non-uniformity in the response reactions of the CO2 ecosystem–atmosphere exchange on the climate anomalies.

Carbon dioxide fluxes of a mountain grassland: Drivers, anomalies and annual budgets

The potential of grasslands to mitigate climate change by carbon (C) sequestration in soils depends on agricultural management and the response of the grassland C cycle to a warming and more variable climate. A 15-year time series of eddy covariance carbon dioxide (CO2) flux measurements on a medium-intensively managed grassland at 1000 m above sea level in Switzerland was analysed to assess how CO2 fluxes respond to environmental drivers as well as grazing and cutting events. Further, the effects of management, recent warming trends and anomalous weather conditions on the annual C sequestration potential were assessed. To this end, C budgets including atmospheric and management-related C fluxes (fertilization, cutting/grazing) were estimated. Generally, the main environmental drivers of CO2 fluxes were light and temperature. The removal of the aboveground canopy by management significantly reduced photosynthesis and induced a saturation in the photosynthetic response to light at lower intensities compared to periods without management. Ecosystem respiration remained largely unaffected by management. With a net ecosystem exchange of −357 (± 76) g C m−2 year−1 and a net biome production of −154 (± 80) g C m−2 year−1 (including management C fluxes), the grassland on average acted as a net C sink. Recent climate warming favors spring CO2 assimilation due to earlier starting vegetation periods. However, the warming also resulted in an increased ecosystem respiration. Further, anomalous and especially unfavorable weather conditions for photosynthesis and regrowth following harvest events induced several periods of an anomalously increased net CO2 release. In the year 2015, such release anomalies contributed to an annual net C loss. Under future climatic conditions, the C sequestration potential at the mountain site will depend on the extent to which spring photosynthesis is offset by such climate-management interactions and a warming-induced increase in ecosystem respiration.

The Little Ice Age, NASA, Colonial Virginia, and the Conundrum of Anomalous Weather Conditions

The relevance of what has been termed as “The Little Ice Age” and its effect on the two earliest English settlements at both Jamestown and the “Lost” Colony of Roanoke in present-day coastal Virginia are still being widely discussed within the scientific community. Recent NASA surveillance findings concerning the events surrounding temperature anomalies at that time, how these affected the Earth’s spheres, as well as their interactions, are still being widely debated and discussed, and new research seeking answers for several growing hypotheses are being actively pursued. This study explores a select group of these ongoing studies. It exposes the potential causes for various situations presented by the Little Ice Age, plus the results and implications these had on all spheres of the planet. It additionally focuses on the problematic preconceived notions that early European settlers had about the conditions awaiting them in a vast and relatively unknown New World, and touches upon the aftermath of making that dangerous miscalculation. It also posits any future implications these recent findings could have on the future of the planet. Finally, it is important to note that like most American and European research studies on this topic, the foci discussed here will not specifically address the localized indigenous populations already living near these two settlements, albeit these groups undoubtedly suffered in a similar manner to their European counterparts. Instead, it will briefly shed light on how Native populations were relevant to the demise of these two English settlements.

Reduction of Air Pollution in Poland in Spring 2020 during the Lockdown Caused by the COVID-19 Pandemic

The COVID-19 pandemic has affected many aspects of human well-being including air quality. The present study aims at quantifying this effect by means of ground-level concentrations of NO2, PM2.5, as well as aerosol optical depth (AOD) measurements and tropospheric NO2 column number density (NO2 TVCD), during the imposed governmental restrictions in spring 2020. The analyses were performed for both urban and non-built-up areas across the whole of Poland accompanied by Warsaw (urban site) and Strzyzow (a background site). The results revealed that mean PM2.5 concentrations in spring 2020 for urban and non-built-up areas across Poland and for Warsaw were 20%, 23%, 15% lower than the 10-year average, respectively. Analogous mean NO2 concentrations were lower by 20%, 18%, 30% and NO2 TVCD revealed 9%, 4%, 9% reductions in 2020 as compared to 2019. Regarding mean AOD, retrieved from MERRA-2 reanalysis, it was found that for the whole of Poland during spring 2020 the reduction in AOD as compared to the 10-year average was 15%. The contribution of the lockdown within total air pollution reduction is not easily assessable due to anomalous weather conditions in 2020 which resulted in advection of clean air masses identified from MERRA-2 reanalysis and Strzyzow observatory.

Frequency Analysis of the Occurrence and Development of Accidents at Oil and Gas Facilities under Abnormal Weather Conditions in the North

In the article the climatic features of the North are analyzed, anomalous weather conditions characterized by the formation of powerful temperature inversions are identified. The influence of adverse anomalous weather conditions on the nature of accidents is justified, and significant changes in the development of gas pipeline accidents in the North than in conditions with a moderate climate are shown. Based on the results of the analysis of gas pipeline accidents that occurred at low temperatures, the main causes of gas pipeline accidents were identified, and “event trees” of gas leakage from the gas pipeline was developed with an assessment of the frequency of emergency scenarios taking into account the abnormal conditions of the North. The most dangerous scenarios of gas pipeline accident evolution have been identified and their risk levels in the zone of the damage factors have been assessed on the basis of acceptable risk criteria.

Industrial applications of selected JFS articles

Industrial applications of selected <i>JFS</i> articles

Potential impacts of the Southern Hemisphere polar vortices on central-eastern China haze pollution during boreal early winter

Understanding the spatial–temporal evolution of China haze pollution (HP) and identifying its precursory signals is of central importance. Based on observational data across central-eastern China (CEC) for the period of 1980–2015, this study finds that HP interannual variations in the CEC region during the most polluted season (December–January) are mainly dominated by a homogeneous pattern with maximum loading centers located over the Central China, Yangtze River Delta, and South China, which accounts for 42.3% of the total variances. The circulations conducive to such polluted mode feature barotropic high anomalies over central-eastern China. Correspondently, the related anomalous weather and circulation conditions with less precipitation, low-level dryer air, weaker surface wind speed, more descending movement, and more upstream transportation of aerosols at the northeast and southeast planks of the anomalous high, leading to the HP frequently occur in the CEC region, and vice versa. Observed evidences show that the combined effects of the Southern Hemisphere tropospheric and stratospheric polar vortices (SHPV) in August and September (AS), can exert profound effects on the HP dominant mode. Notable circulation anomalies associated with the combined effects of the SHPV, prevailing over the ocean off the south-west Western Australia, can induce sea surface temperature (SST) anomalies around the ocean off the south-west Western Australia. This anomalous SST pattern in AS can persist into the following early winter and impact the HP variations by modulating the Hadley cell and correspondently circulation anomalies over central-eastern China. Based on the preseason SHPV signal, we establish a physical-empirical seasonal prediction model to predict the HP dominant mode variations. The hindcast shows a promising prediction skill. Since the regional PV anomalies linked to the combined effects of the SHPV could be monitored in preceding autumn, the HP over the CEC in early winter can be forecasted in real-time by this empirical model.

Extreme rainfall event in the Northeast coast of Brazil: a numerical sensitivity study

This study investigates an extreme rainfall event which occurred in Northern Brazil (NEB) between 20 and 30th 2017 May causing several deaths and making thousands homeless. Based on a suite of microphysics and planetary boundary layer (PBL) schemes based on the WRF model, it is demonstrated that anomalous weather conditions are characterized by significant upward and eastward wind flow. Omega differences with respect to climatological conditions showed values up to − 0.04 Pa/s and wind up to 6–8 m/s in consonance with higher precipitation in May in the NEB coast. The cumulative rainfall for 11 days was higher than 500 mm in some locations, as measured by weather stations. These conditions were simulated by the WRF model under different physics parameterization schemes. In total 24 experiments with WRF were implemented. Non-local PBL demonstrated better performance than the local PBL. Moreover, the rainfall was concentrated in small portions of the region, and the local scheme limited the WRF conditions to estimate the correct maximum precipitation location. The Morrison scheme performed better compared to the other schemes. Results presented here show that the correct choices of the microphysics and PBL parameterizations are fundamental to obtain good simulation/forecast, especially for extreme rainfall events. This study demonstrates that regional modeling is crucial to provide accurate information to forecasters and decision makers to plan actions which hamper catastrophic situations such as landslides and floods in high-risk regions.

The Predictability of Blocking Character in the Northern Hemisphere Using an Ensemble Forecast System

Introduction:Some weather extremes are the result of atmospheric blocking, which can be responsible for the stagnation of weather patterns. These large-scale quasi-stationary mid-latitude flow regimes can result in significant temperature and precipitation anomalies over the regions that the blocking event impacts or in the upstream and downstream regions.Methods:The ability to predict periods of anomalous weather conditions due to atmospheric blocking is a major problem for medium-range forecasting. Analyzing the National Centers for Environmental Prediction (NCEP) Ensemble 500-hPa pressure level heights (240 hrs.) ten-day forecasts, and using the University of Missouri blocking archive to identify blocking events, the forecasted onset, duration, and intensity of model blocking events are compared to observed blocks.Results and Discussion:The observed blocking events were identified using the University of Missouri blocking archive. Comparing these differences using four Northern Hemisphere case studies occurring over a one-year period across the Northern Hemisphere has shown the continued need for improvement in the duration and intensity of blocking events. Additionally, a comparison of the block intensity to a diagnostic known as the Integrated Regional Enstrophy (IRE) was performed in order to determine if there is a correlation between IRE and these quantities.Conclusion:Having a better understanding of block persistence and their associated anomalies can help society prepare for the damage they can cause.

Variability of the antioxidant properties of Berberis fruits depending on the plant species and conditions of habitat

Plant fruits, leaves, stems, and other parts are of high nutritional value, and are the source of physiologically active compounds, which can contribute to the treatment of many diseases caused by oxidative stress. Enrichment of the species spectrum of the fruit plants expands the possibilities of their use in dietary nutrition and human treatment. Unfortunately, the introduction of the new fruit plant species in industrial gardens in the Steppe Dnieper is limited to a large extent by the unfavorable climate. In this regard, the assessment of the possibility of realizing the genetic potential of fruit plants from different geographical areas in the steppe climate acquires both scientific and practical significance. The study was conducted on the basis of the fruit plants collection collection of the Botanical Garden of the DNU including four introduced species and one natural species from the genus Berberis. The anomalous weather conditions during the growing season of 2017 (snowfall in April followed by a drought in June) were accompanied by an earlier stage appearance of leaves, flowering and fruit ripening of all introduced plants, especially the Asian species B. amurensis and B. koreana, compared to the native species B. vulgaris. In accordance with the results obtained, fresh weight of the ripe fruits of Berberis species decreased in the order of B. amurensis &gt; B. vulgaris &gt; B. canadensis &gt; B. koreana &gt; B. x declinata. The highest total phenolics content, determined in the isopropanolic fruit extracts by Folin – Ciocalteau assay, was found in the fresh ripe fruits of B. koreana (1362 ± 66 mg GAE/100 g WW), followed by B. x declinata and B. vulgaris fruits (91% and 77% of the B. koreana phenolics content respectively). The highest total flavonoids content determined using the aluminum chloride method was revealed in the fruits of B. koreana (210 ± 6 mg RE/100 g FW) exceeding the content in fruits of other Berberis species by 1.1–2.1 times, while the lowest value (103 ± 4 mg RE/100 g FW) was found in the fruits of B. amurensis. The total reducing power, determined by RP assay, varied in the range from 5.0 to 9.6 mg AAE/100 g DW, and the highest levels were found in the fruits of B. koreana and B. x declinata (respectively, 9.6 ± 0.6 and 8.6 ± 0.5 mg AE/100 g DW) exceeding the reducing capacity of other Berberis species by 1.7–1.9 times. In the fruits of genus Berberis species strong positive correlation was found between the total reducing power and the total content of phenols (r = 0.87), as well as between the reducing power and the total content of flavonoids (r = 0.84). High correlation coefficients confirm the significant contribution of the Berberis fruit phenolic compounds, including the flavonoids, to the antioxidant capacity. So, the study results showed that fruits of all examined Berberis species can be an easily accessible source of antioxidants, however, the antioxidant capacity of fruits decreased in order of B. koreana &gt; B. x declinata &gt; B. vulgaris &gt; B. amurensis &gt; B. canadensis.

ВЛИЯНИЕ ИНСОЛЯЦИИ НА ПРОДУКТИВНОСТЬ ЛИСТОВОГО АППАРАТА И ВОДНЫЙ РЕЖИМ АБРИКОСА И АЛЫЧИ ПРИ АНОМАЛЬНЫХ ПОГОДНЫХ УСЛОВИЯХ

ВЛИЯНИЕ ИНСОЛЯЦИИ НА ПРОДУКТИВНОСТЬ ЛИСТОВОГО АППАРАТА И ВОДНЫЙ РЕЖИМ АБРИКОСА И АЛЫЧИ ПРИ АНОМАЛЬНЫХ ПОГОДНЫХ УСЛОВИЯХ

An Assessment of the ECMWF Extreme Forecast Index for Water Vapor Transport during Boreal Winter

Abstract Early awareness of extreme precipitation can provide the time necessary to make adequate event preparations. At the European Centre for Medium-Range Weather Forecasts (ECMWF), one tool that condenses the forecast information from the Integrated Forecasting System ensemble (ENS) is the extreme forecast index (EFI), an index that highlights regions that are forecast to have potentially anomalous weather conditions compared to the local climate. This paper builds on previous findings by undertaking a global verification throughout the medium-range forecast horizon (out to 15 days) on the ability of the EFI for water vapor transport [integrated vapor transport (IVT)] and precipitation to capture extreme observed precipitation. Using the ECMWF ENS for winters 2015/16 and 2016/17 and daily surface precipitation observations, the relative operating characteristic is used to show that the IVT EFI is more skillful than the precipitation EFI in forecast week 2 over Europe and western North America. It is the large-scale nature of the IVT, its higher predictability, and its relationship with extreme precipitation that result in its potential usefulness in these regions, which, in turn, could provide earlier awareness of extreme precipitation. Conversely, at shorter lead times the precipitation EFI is more useful, although the IVT EFI can provide synoptic-scale understanding. For the whole globe, the extratropical Northern Hemisphere, the tropics, and North America, the precipitation EFI is more useful throughout the medium range, suggesting that precipitation processes not captured in the IVT are important (e.g., tropical convection). Following these results, the operational implementation of the IVT EFI is currently being planned.

Situating 1816, the ‘year without summer’, in the UK

The immediate local impacts of the eruption of Mount Tambora, Sumbawa, Indonesia in April 1815 were devastating, resulting in the loss of an estimated 60 000 lives on this and neighbouring islands. However, the longer term effects of the largest known historical eruption on global weather and climate and the related consequences for human health and wellbeing have maintained the prominence of the eruption in public memory. Among the most notable effects were global weather anomalies the following year, which has come to be referred to as ‘the year without summer’. Scholars across the sciences and humanities continue to investigate the eruption, seeking insights into the likely meteorological and societal impacts of future volcanic eruptions. The bicentenary of the ‘year without summer’ in 2016 provides a timely moment to revisit this weather episode. In this paper, we draw on a range of archival materials and contemporary publications to reconstruct the weather year and explore how the summer of 1816 was experienced and recorded across the UK. We also wish to demonstrate the importance of historical contingency in understanding the potential implications of the event at the local level, and of situating events within their appropriate temporal context. We do this by considering the summer of 1816 as set against the wider weather and cultural contexts of the 1810s. Our findings illustrate that in a UK context, summer 1816 was characterised by unusual and extreme weather events. Importantly it also took place within a sequence of years that were similarly replete with anomalous and challenging weather conditions.

Phages in the global fruit and vegetable industry.

From recent articles, we have learned that phages can constitute a promising alternative in the food industry to eliminate bacterial pathogens from seedlings in greenhouse and field environments, as well as from fresh-cut food products. The fruit and vegetable industry requires quite a different approach than the meat or dairy industry. Several factors can inhibit efficacy of phage treatment such as plant watering or washing ready-to-eat products (water may dilute therapeutic doses), UV irradiation or extensive spreading of phytopathogens by wind, insects or even humans. Spontaneously occurring anomalous weather conditions in different parts of the world also may have an enormous impact on phage persistence in cultivations and on yields. Despite that, some phage preparations are commercially available and, without doubt, are much safer than chemical treatments. Along with increasing worldwide fruit and vegetable consumption, plant diseases and human foodborne illnesses are becoming a serious economic problem, resulting in a focus on optimization of phage treatment.

Formation process of the widespread extreme haze pollution over northern China in January 2013: Implications for regional air quality and climate

In this study, we present a regional insight into characteristics and formation process of the widespread extreme haze pollution in northern China during January of 2013 using integrated satellite observations and ground measurements. Different from common regional pollution, dense haze clouds during the most polluted period not only wandered over northern China for more than one week, but also exhibited large spatial variations with some abrupt peak values in Beijing. High UV Aerosol Index (UVAI) values >2.5 indicate prevalent absorbing aerosols in upper part of the haze clouds. CALIPSO vertical detection shows that the haze layers were more than 3 km thick, with strong extinction within 1 km near surface and elevated dust layers above. Top of the more than 2 km thick dust plumes can reach 5 km, having a substantial contribution to the haze clouds. Movement of high aerosol loading regions with aerosol optical depth (AOD) exceeding 2.0 shows a notable superposition of different pollution processes within boundary layer, which largely enhanced the haze pollution. Peak value of PM10 in industrial cities of Hebei was around 1000 μg/m3, almost twice of that in usual pollution. Subsequent peak values of PM10 from south to north confirm the intense regional transport, which could be the main cause of sudden record-breaking particle concentration in Beijing. Anomalous weather conditions facilitated the unusual heavy pollution became extremely severe. Our results indicate close connections between variation of atmospheric circulation and the regional heavy pollution over northern China.